Electromyographic assessment of muscle fatigue in massive rotator cuff tear.

Shoulder muscle fatigue has not been assessed in massive rotator cuff tear (MRCT). This study used EMG to measure fatigability of 13 shoulder muscles in 14 healthy controls and 11 patients with MRCT. A hand grip protocol was applied to minimise artifacts due to pain experience during measurement. The fatigue index (median frequency slope) was significantly non-zero (negative) for anterior, middle, and posterior parts of deltoid, supraspinatus and subscapularis muscles in the controls, and for anterior, middle, and posterior parts of deltoid, and pectoralis major in patients (p ≤ 0.001). Fatigue was significantly greater in patients compared to the controls for anterior and middle parts of deltoid and pectoralis major (p ≤ 0.001). A submaximal grip task provided a feasible way to assess shoulder muscle fatigue in MRCT patients, however with some limitations. The results suggest increased activation of deltoid is required to compensate for lost supraspinatus abduction torque. Increased pectoralis major fatigue in patients (adduction torque) likely reflected strategy to stabilise the humeral head against superior subluxing force of the deltoid. Considering physiotherapy as a primary or adjunct intervention for the management of MRCT, the findings of this study generate a base for future clinical studies aiming at the development of evidence-based protocols.

Sliding external fixator "a product design and cadaveric experiment".

BACKGROUND: External fixation spanning a joint like the elbow, while maintaining joint mobility, is a well-established practice, and it could be done with a variety of external fixation systems. In current systems, correct identification of the elbow center of rotation under X-ray guidance with lateral views is mandatory. If the center of rotation of the fixator is not aligned with that of the elbow joint, the assembly will not work. This new design idea aims to propagate the principle of sliding external fixation applied on the extensor side of a joint, with the limbs of the fixator being able to slide in and out during joint extension and flexion, respectively, without hindering the joint movement, without the need to use X-ray guidance to identify the center of rotation. MATERIALS AND METHODS: A cadaveric experiment was carried on using a sliding fixator prototype applies on two cadaveric elbow specimens, which were tested though the arc of movement. RESULTS: Assembling the fixator over the intact elbows without identifying the center of rotation did not impede the joint movement. Furthermore, after surgical dislocation of the elbow, the external fixator was able to keep the joint congruent, throughout the movement arc. CONCLUSION: It was possible to apply a sliding external fixator on the extensor surface of a joint without identifying the center of rotation, and that does not seem to impede the joint movement, while can still keep the dislocated joint congruent despite attempted distraction.

Shoulder muscle activation and fatigue during a controlled forceful hand grip task.

PURPOSE: Reliable electromyographic evaluation of the shoulder in common painful conditions is a major challenge due to a reduced range of movement and pain-related muscle inhibition. This study investigates the use of a hand grip task for the assessment of shoulder muscle activation. METHODS: Muscle activity and fatigue for supraspinatus and infraspinatus muscles were measured in 16 healthy controls using fine-wire electrodes during a controlled gripping task at 50% of maximum voluntary contraction, in a standardized sitting and arm position. Changes in muscle activity and fatigue were measured by the time-slope of root mean square amplitude and median frequency, respectively. RESULTS: A significant positive amplitude slope (p<0.01) was found for both supraspinatus and infraspinatus, indicating that the task resulted in increasing muscle activity. Judging by the median frequency slope, there was no sign of fatigue progression. CONCLUSION: A standardized hand grip task in a neutral position activates key rotator cuff muscles. This might provide a method for electromyographic assessment of shoulder girdle muscles which avoids problems due to pain-related limitation of movement, and might be useful in the development and monitoring of shoulder rehabilitation strategies.

Major joint replacement. A model for antithrombotic drug development: from proof-of-concept to clinical use.

AIM: Development of antithrombotic compounds has traditionally been performed in patients undergoing total hip and knee replacement surgery. A high number of asymptomatic deep-vein thromboses are radiologically detectable, and bleeding and other adverse events (AE) are easy to observe. However, standardization of study procedures and endpoints in early proof-of-concept studies and late pure clinical endpoint studies has been lacking. This has made comparison between studies difficult, economic analyses speculative and potential benefits of applying the drug regimen in non-selected patients uncertain. In this paper, the International Surgical Thrombosis Forum proposes a strategy for the clinical investigation of new pharmacological agents for the prophylaxis of postoperative thrombotic events. METHODS: First, dose titration safety studies of short duration, in highly selected patients using objective venographic endpoints are recommended. Bleeding should be divided into the quantified volume of surgical bleeding and other adjudicated clinical bleeding events. The number of AE should be described for each dose step and classified according to International Coding of Diagnoses (ICD). Second, a dose confirmatory study of moderate exposure period and sufficient follow-up time is recommended. The exclusion criteria should be restricted to contraindications of the compared drugs and technical procedure. RESULTS: The efficacy, bleeding and AE should be similar to those used in dose-titration studies. In addition, the failure rate of the drug to exert its effect and the net clinical benefit should be calculated. CONCLUSION: Finally, trials with simple clinical endpoints and long follow-up should be conducted to evaluate the potential benefits of the drug-regimen in non-selected populations.

Unlinked elbow arthroplasty as primary treatment for fractures of the distal humerus.

This study reviews our experience with primary total elbow arthroplasty in the management of acute distal humeral fractures by use of the iBP unlinked elbow prosthesis. We followed up 9 elbows in 9 patients (including 2 with rheumatoid arthritis), with a mean age of 73 years, for a mean of 3.5 years. Functional outcome was assessed with the Mayo Elbow Performance Score and the recently developed Liverpool Elbow Score. Clinical examination and radiologic assessment were performed by an independent surgeon. All elbows were stable at the latest follow-up examination, all patients were able to perform daily activities, and pain relief was satisfactory. The median value for the Mayo Elbow Performance Score was 95 (range, 65-100). This is the first report of the use of an unlinked prosthesis for the treatment of distal humeral fractures. Our results show that this method of treatment provides a reliable and effective way of dealing with these very difficult fractures when internal fixation is not a viable option.

Oral dabigatran etexilate vs. subcutaneous enoxaparin for the prevention of venous thromboembolism after total knee replacement: the RE-MODEL randomized trial.

BACKGROUND: Oral anticoagulants, such as dabigatran etexilate, an oral, direct thrombin inhibitor, that do not require monitoring or dose adjustment offer potential for prophylaxis against venous thromboembolism (VTE) after total knee replacement surgery. METHODS: In this randomized, double-blind study, 2076 patients undergoing total knee replacement received dabigatran etexilate, 150 mg or 220 mg once-daily, starting with a half-dose 1-4 hours after surgery, or subcutaneous enoxaparin 40 mg once-daily, starting the evening before surgery, for 6-10 days. Patients were followed-up for 3 months. The primary efficacy outcome was a composite of total VTE (venographic or symptomatic) and mortality during treatment, and the primary safety outcome was the incidence of bleeding events. RESULTS: The primary efficacy outcome occurred in 37.7% (193 of 512) of the enoxaparin group versus 36.4% (183 of 503) of the dabigatran etexilate 220 mg group (absolute difference, -1.3%; 95% CI, -7.3 to 4.6) and 40.5% (213 of 526) of the 150 mg group (2.8%; 95% CI, -3.1 to 8.7). Both doses were noninferior to enoxaparin based on the pre-specified noninferiority criterion. The incidence of major bleeding did not differ significantly between the three groups (1.3% versus 1.5% and 1.3% respectively). No significant differences in the incidences of liver enzyme elevation and acute coronary events were observed during treatment or follow-up. CONCLUSIONS: Dabigatran etexilate (220 mg or 150 mg) was at least as effective and with a similar safety profile as enoxaparin for prevention of VTE after total knee-replacement surgery.

Strength and fatigability of selected muscles in upper limb: assessing muscle imbalance relevant to tennis elbow.

PURPOSE: The aetiology of tennis elbow has remained uncertain for more than a century. To examine muscle imbalance as a possible pathophysiological factor requires a reliable method of assessment. This paper describes the development of such a method and its performance in healthy subjects. We propose a combination of surface and fine-wire EMG of shoulder and forearm muscles and wrist strength measurements as a reliable tool for assessing muscle imbalance relevant to the pathophysiology of tennis elbow. METHODS: Six healthy volunteers participated. EMG data were acquired at 50% maximal voluntary isometric contraction from five forearm muscles during grip and three shoulder muscles during external rotation and abduction, and analysed using normalized median frequency slope as a fatigue index. Wrist extension/flexion strength was measured using a purpose-built dynamometer. RESULTS: Significant negative slope of median frequency was found for all muscles, with good reproducibility, and no significant difference in slope between the different muscles of the shoulder and the wrist. (Amplitude slope showed high variability and was therefore unsuitable for this purpose.) Wrist flexion was 27+/-8% stronger than extension (mean+/-SEM, p=0.006). CONCLUSION: This is a reliable method for measuring muscle fatigue in forearm and shoulder. EMG and wrist strength studies together can be used for assessing and identifying the muscle balance in the wrist-forearm-shoulder chain.

Suture anchors for treatment of sternoclavicular joint instability.

Instability of the sternoclavicular joint is a difficult problem to treat and can present with gross limitation in activities. Eight sternoclavicular joint stabilization procedures were performed over an 8-year period. The patients' ages ranged from 16 to 48 years (mean, 23.5 years). The indication for stabilization was pain associated with instability of the sternoclavicular joint. The joint was stabilized by use of suture anchors on the manubrium and capsular plication. The functional outcome was evaluated by use of the Constant score and patient-based Oxford Shoulder Questionnaire. At a mean follow-up of 4.5 years (range, 1-7.6 years), none of the patients had instability at the sternoclavicular joint, and all except one had returned to their previous employment. The Oxford score was 16 (range, 12-38). The mean Constant score was 74.88 (range, 33-87). We had only 1 poor result (Constant score of 33). Stabilization of the sternoclavicular joint can safely be performed by use of suture anchors. The technique is recommended for symptomatic sternoclavicular joint instability.

Mid term results of PlantTan plate in the treatment of proximal humerus fractures.

This prospective study evaluates the clinical efficacy of a special implant, PlantTan plate used for fixation of displaced proximal humerus fractures. The PlantTan plate was used for internal fixation of closed displaced proximal humeral fractures in 68 patients from September 1999 to June 2002, in a University Hospital. One of the surgeries was for a non-union, and five patients were lost to follow-up. The patients' ages ranged from 19 to 76 years (mean 61 years and median 66 years). Of the remaining 62 patients, 42 were female and 20 were male. As defined using the Neer classification 19 patients had two part, 37 three part and 6 had four part fractures. Median follow-up was 19 months (11-38). The outcome was assessed using radiographs, American Shoulder and Elbow Surgeons (ASES) score and Hospital for Special Surgery (HSS) scoring system. Fifty-two patients achieved union in a median of 8 weeks. The median cumulative score of activities of daily living of ASES was 20.4/30 (13-27). According to HSS, 11 scored excellent, 26 good, 14 fair and 11 scored poor. Eight patients had fixation failure and two developed avascular necrosis. Eleven patients developed an infection. Six patients developed an infection resulting in implant removal. One had a transient and one permanent axillary nerve palsy. Since the PlantTan plate provides stability, early active rehabilitation can be instituted. The implant is distally placed reducing impingement symptoms. However, the implant requires wide surgical exposure, is bulky and has an unacceptable infection rate. The fixation failure is high in patients with osteoporosis. In view of the above encountered problems, the implant has been discontinued in our hospital.

Botulinum toxin injection in the treatment of tennis elbow. A double-blind, randomized, controlled, pilot study.

BACKGROUND: A recent report has suggested that local injection of botulinum toxin type A is an effective method of treatment for chronic tennis elbow. The toxin is thought to provide temporary paralysis of the painful common extensor origin, thereby allowing a healing response to occur. To test this theory, we performed a double-blind, randomized, controlled, pilot trial comparing injections of botulinum toxin type A with those of a placebo (normal saline solution) in the treatment of chronic tennis elbow. METHODS: Forty patients with a history of chronic tennis elbow for which all conservative treatment measures, including steroid injection, had failed were randomized into two groups. Half the patients received 50 units of botulinum toxin type A, and the remainder received normal saline solution. The intramuscular injections were performed 5 cm distal to the maximum point of tenderness at the lateral epicondyle, in line with the middle of the wrist. The two solutions used for the injections were identical in appearance and temperature. The results of a quality-of-life assessment with the Short Form-12 (SF-12), the pain score on a visual analogue scale, and the grip strength measured with a validated Jamar dynamometer were recorded before and three months after the injection. RESULTS: Three months following the injections, there was no significant difference between the two groups with regard to grip strength, pain, or quality of life. CONCLUSIONS: With the numbers studied, we failed to find a significant difference between the two groups; thus, we have no evidence of a benefit from botulinum toxin injection in the treatment of chronic tennis elbow.

Development and validation of an elbow score.

OBJECTIVES: Few of the questionnaires available for evaluating the function and clinical state of the elbow have been validated. An ideal score would be consistent, sensitive, reliable and elbow-specific, incorporating both patient perception and clinician assessment. This was our aim. METHODS: Items were generated using 25 patients and expert opinion, and reduced using 25 new patients to yield a nine-item patient questionnaire and a six-item clinical evaluation (of strength, motion and ulnar nerve involvement). This was validated using 63 new patients (of whom 28 were studied twice without therapy and 18 were studied again after appropriate surgery). RESULTS: The test-retest reliability coefficient of determination (R2 = 0.93) and internal consistency (Cronbach's alpha = 0.98) were both good. Convergent validity was attested by good correlations with other scores, the Disabilities of Arm, Shoulder and Hand Questionnaire (DASH) and the Nottingham Health Profile (NHP) (physical) (R2 = 0.62 and 0.29, P < 0.0005). Sensitivity to change was demonstrated by correlating preoperative-postoperative changes to those in DASH and NHP (physical) (R2 = 0.50 and 0.27, P < 0.04). CONCLUSION: This is a reliable, internally consistent score, correlating well with other, non-elbow specific scores and sensitive to change on treatment.

The management of facial injuries in rugby union.

BACKGROUND: There are as yet no guidelines in rugby union for the management of facial lacerations which account for one-third of total injuries sustained by players. METHOD: We devised a questionnaire to establish the current standards in rugby union clubs in England. The questionnaire covered such issues as inadequate wound cleansing, inappropriate suture material, the use of sterile suture equipment, and advice required for suture removal. RESULTS: We recommend that a dedicated medical room should be available in all clubs, the doctor should always wear gloves, and local anaesthetic and sterile suture packs and instruments should be provided.

Muscle oxygenation and ATP turnover when blood flow is impaired by vascular disease.

31P magnetic resonance spectroscopy (31P MRS) and near-infrared spectroscopy (NIRS) are combined to study interactions between oxidative ATP synthesis rate, perturbation of the creatine kinase equilibrium, and cellular oxygenation state in calf muscle of normal subjects and patients with muscle perfusion impaired by peripheral vascular disease.

The kinematics and kinetics of slipknots for arthroscopic Bankart repair.

An apparatus has been developed to enable the in vitro measurement of the kinematics and kinetics of a slipknot, both while the knot is being tightened and with the knot in place and the tension removed. During tightening, the apparatus provides a linearly increasing resistance, which may be considered analogous to the resistance experienced when the labrum is drawn toward and apposed to the edge of the glenoid cavity during a Bankart repair. The tension to close the knot is measured with a tensiometer, in tandem with the closure of the capsule model onto the bone anchor, which is measured with a datalogger. The tightening tension was limited to 25 N and intraoperator and interoperator comparisons were made for four knots tied by six participants. Failure of a knot was taken to be reverse slippage of 2 mm. A second criterion of ease of slide was used to assess each knot. We found wide interoperator variability with regard to slipknot tying. A methodology for quality control of slipknot tying is presented.

Mitochondrial function and oxygen supply in normal and in chronically ischemic muscle: a combined 31P magnetic resonance spectroscopy and near infrared spectroscopy study in vivo.

PURPOSE: We used (31)P magnetic resonance spectroscopy (MRS) and near-infrared spectroscopy (NIRS) as a means of quantifying abnormalities in calf muscle oxygenation and adenosine triphosphate (ATP) turnover in peripheral vascular disease (PVD). METHODS: Eleven male patients with PVD (mean age, 65 years; range, 55-76 years) and nine male control subjects of similar age were observed in a case-control study in vascular outpatients. Inclusion criteria were more than 6 months' calf claudication (median, 1.5 years; range, 0.6-18 years); proven femoropopliteal or iliofemoral occlusive or stenotic disease; maximum treadmill walking distance (2 km/h, 10 degrees gradient) of 50 to 230 m (mean, 112 m); ankle-brachial pressure index of 0.8 or less during exercise (mean, 0.47; range, 0.29-0.60). Exclusion criteria included diabetes mellitus, anemia, and magnet contraindications. Simultaneous (31)P MRS and NIRS of lateral gastrocnemius was conducted during 2 to 4 minutes of voluntary 0.5 Hz isometric plantarflexion at 50% and 75% maximum voluntary contraction force (MVC), followed by 5 minutes recovery. Each subject was studied three times, and the results were combined. RESULTS: Compared with control subjects, patients with PVD showed (1) normal muscle cross-sectional area, MVC, ATP turnover, and contractile efficiency (ATP turnover per force/area); (2) larger phosphocreatine (PCr) changes during exercise (ie, increased shortfall of oxidative ATP synthesis) and slower PCr recovery (47% +/- 7% [mean +/- SEM] decrease in functional capacity for oxidative ATP synthesis, P = .001); (3) faster deoxygenation during exercise and slower postexercise reoxygenation (59% +/- 7% decrease in rate constant, P = .0009), despite reduced oxidative ATP synthesis; (4) correlation between PCr and NIRS recovery rate constants (P < .02); and (5) correlations between smaller walking distance, slower PCr recovery, and reduced MVC (P < .001). The precision of the key measurements (rate constants and contractile efficiency) was 12% to 18% interstudy and 30% to 40% intersubject. CONCLUSION: The primary lesion in oxygen supply dominates muscle metabolism. Reduced force-generation in patients who are affected more may protect muscle from metabolic stress.

The rising number of underfoot accidents after the menopause causes both fractures and non-fracture injuries.

To test our hypothesis that the onset of the menopause would be associated with an increased number of underfoot accidents in the female population for both fracture and non-fracture injuries, we analysed 90061 accidents recorded by the Home Accident Surveillance System and classified them as to (a) whether a fracture resulted, and (b) whether they were 'underfoot'. We defined 'underfoot' accidents to have an event such as a trip, slip, missed footing, twisted or turned ankle, on the level or on stairs. All other accidents, including falls from or off structures, or falls caused by medical conditions were classified as 'not underfoot'. Overall, 51.3% of women and 32% of men were injured in underfoot accidents. There was an increase with age in the percentage of fractures in both men and women, mainly due to an increased risk of fracture in underfoot accidents: underfoot accidents caused 75.9% of all fractures in women and 55.4% in men. The number of women who had fractures following underfoot accidents increased sharply after the age of 50 years, and the number continued to rise up to 80 years. The number of non-fracture injuries in elderly women from underfoot accidents also increased with age. Osteoporosis on its own does not explain our result, and changes in muscle strength and reaction time, with age in both men and women, and at a greater rate in postmenopausal women, may be an important factor in underfoot accidents.

Expression of Schwann cell-specific proteins and low-molecular-weight neurofilament protein during regeneration of sciatic nerve treated with neurotrophin-4.

Neurotrophin-4 acts as a potent survival factor for subpopulations of motoneurons. To investigate its effect on Schwann cell sheath and axonal proteins during peripheral nerve regeneration, sciatic nerves in adult rats were transected and repaired, and fibrin glue containing neurotrophin-4 injected around the repair site. At 5, 15, 30 and 60 days after repair, 5-mm nerve segments distal to the repair were collected, and western blotting was used to measure myelin-associated glycoprotein, myelin basic protein and low-molecular-weight neurofilament protein. In control groups these dramatically declined at 5 and 15 days then increased from 30 and 60 days. However, in the neurotrophin-4 group there was a significant increase (to several times basal values) in myelin-associated glycoprotein and myelin basic protein at 5-15 days. The relatively small increases (<7%) in Schwann cell numbers suggest that this is mainly due to increased synthesis per cell. The neurotrophin-4 group also showed a small but significant increase at 15 days in low-molecular-weight neurofilament protein, which however remained much lower than basal. We conclude that neurotrophin-4 regulates the expression of myelin-associated glycoprotein, myelin basic protein, and to a lesser extent low-molecular-weight neurofilament protein, during peripheral nerve regeneration.